PURPOSE: To obtain a ultra-lightweight GRC member having mechanical strength comparable to or higher than those of conventional concrete materials etc., and about half in weight compared to conventional GRC.

CONSTITUTION: This ultra-llghtweight GRC member has a specific gravity of 1.0-1.2, flexural strength of 100-130kgf/cm2 and compressive strength of 200-300 kgf/cm2, being obtained from 100 pts.wt. of cement, 20-100 pts.wt. of lightweight aggregates, 5-20 pts.wt. of a synthetic resin emulsion (solid concentration at 45wt.%), 1-6 pts.wt. of glass fiber, 0.1-2 pts.wt. of a high-performance water reducing agent, 0.1-1.0 pt.wt. of a defoaming agent, 0.1-0.3 pts.wt. of a water-soluble resin, and 30-60 pts.wt. of water. Specifically, this GRC member is obtained by the following process: cement is dry-mixed with lightweight aggregates in advance, the mixture is incorporated with a synthetic resin emulsion, high- performance water reducing agent, defoaming agent and water-soluble resin followed by water, and the resultant mixture is kneaded and then mixed with glass fibers and further kneaded, and the resultant mixture is cast into a shuttering followed by conducting a steam curing and then demolding.